When installing FCS2 you do not have to enter anything to get quicktime pro, it automatically unlocks the pro features. Simply open the quicktime player and you will see the pro features unlocked.
As for some of your other questions.
[Jason Lyons] “I wonder if it is as simple as downloading Quicktime and installing”
Thats NOT so simple as you think. To downgrade to a older version you must do an archive and instal on the OS.
[Jason Lyons] “Just wondering how it will know its QT Pro as you are not prompted to enter a key anymore”
Again just open quicktime player and you will see the pro features unlocked. Those features are actually there with out quicktime pro, but quicktime will NOT let you use them.
There are no “technical solutions” to your “artistic problems”.
Don’t let technology get in the way of your creativity!